BitMask OptionSets w/ Associated Structures

OptionSetInfo.swift

struct WeekdaySet: OptionSet {
    struct Info {
        var name: String
        var index: Int
    }
    static var info:[Int:Info] = [:]
    
    let rawValue: UInt8

    init(rawValue: UInt8) {
        self.rawValue = rawValue
    }

    init(_ name: String, _ ndx: UInt8) {
        self.rawValue = (1 << ndx)
        WeekdaySet.info[self.index] = Info(name: name, index: self.index)
    }

    var index: Int { rawValue.trailingZeroBitCount }
    var info: Info { return Self.info[index]! }
    
    static let sunday        = WeekdaySet("sunday", 1)
    static let monday        = WeekdaySet("monday", 2)
    static let tuesday       = WeekdaySet("tuesday", 3)
    static let wednesday     = WeekdaySet("wednesday", 4)
    static let thursday      = WeekdaySet("thursday", 5)
    static let friday        = WeekdaySet("friday", 6)
    static let saturday      = WeekdaySet("saturday", 7)
}